The comedy pair are recording a version of the Proclaimers' 'I'm Gonna Be (500 Miles)', and hope to emulate the success of Kay's million-selling version of Tony Christie's 'Amarillo'.
They are known to be fans of the Proclaimers, led by Scottish brothers Craig and Charlie Reid. Lucas wrote sleeve notes for their greatest hits, while Kay joined the band on stage when they performed at Live 8 last year.
The band themselves, who still have a cult following and an enduring commitment to charity, will provide backing vocals for the release.
A Comic Relief spokesman told the Daily Mirror: "The Comic Relief single is hugely important to us, it is a great fundraiser."